Prior to the present invention, finish covers for a wide variety of products have been made from different plastic materials layered or otherwise combined by various processes into desired shapes and finishes. For example, many modern vehicles have instrument panels with special top covers that provide different degrees of softness and tactile feel to meet customer requirements. In general three major processes and constructions are employed for such top covers as follows: (1) a "super soft" top cover made from a hard structural plastics retainer as a substrate or base, an intermediate polyurethane foam, and a roto--cast or slush molded vinyl outer skin, (2) a "soft" top cover generally comprised of a hard plastic retainer as a substrate and a bi-laminate vinyl skin that utilizes an expanded vinyl foam on the underside of the skin, and (3) a "soft touch" top cover that comprises a molded structural plastic as a base and with a top coat of "soft touch" paint applied thereto.
While each of these three processes provide desirable finishing covers and other like products, "super soft" top cover manufacturing involves relatively complex production procedures generally requiring special tooling for foaming the polyurethane and for the outer skin application. Furthermore, the aesthetic requirements of this process renders it the most costly of the three processes identified above. The "soft" top cover process is a time consuming and labor intensive method, particularly, since it requires the application of an adhesive to the skin and a thermoforming process to bond the components together. The "soft touch" top covers use a paint coating that is also labor intensive and generally compares cost wise with the "super soft" process. In any event, the plastics components of the "super soft" and "soft" covers are not from the same family of plastics materials so that separation of the different plastics is necessary since different procedures and solvents are used for recycling different plastics. Accordingly, recycling is difficult and expensive. This is also the case with the addition of the "soft touch" paint which introduces another incompatible material into the life cycle management of a "soft touch" cover.
In view of the above considerations and others of the following specification, an object, feature and advantage of this invention is to provide a new and improved process for producing a soft touch top cover of a plurality of different plastics materials but from the same family of materials to form a quality part with good interior support and desirable outer surface qualities which after completion of service life is readily and easily recyclable as a unitized part to provide improved life cycle management.
It is another feature, object and advantage to provide a new and improved soft touch top cover that has a "soft to touch" outer skin extending over and integrated with a relatively hard and rigid or semi rigid substrate providing a stabilizing base member.
Still another feature, object and advantage of this invention is to provide a new and improved outer cover and method to produce a multi layer cover of a plurality of different plastics materials that are from the same family of recyclable plastics material which are fused together and which can be readily recycled.
Another feature, object and advantage of this invention is to make a finishing cover of two or more layers of separate and different plastics materials from the same family of plastics which are compatible and recyclable. This allows the finish cover to be recycled as a unitized member without the necessity of separating the plastics layers from one another and handling them as different materials. In this invention, one of the cover components provides a relatively thick substrate for structural rigidity while the outer component layer is a relatively thin outer sheet with a textured outer surface providing a "soft feel or touch" sensation that one may experience when touching and rubbing their hand across the outer surface thereof.
In the preferred embodiment of this invention, a pair of plastics extruders are employed with a co-extrusion blow molding unit for producing a co-extruded parison formed of two different materials of the same plastics family. One extruder unit processes the base plastics material that is forced through a mandrel of a co-extrusion blow molding unit to form the core of the parison while an associated satellite extruder processes the finishing plastics material and forces it through the mandrel simultaneously to form the outer skin of the parison. When the parison has grown to a sufficient size and the molding tools are being closed, the end is pinched off and low pressure air is injected into the parison so that the parison can fully conform to the configuration of the mold cavity. The closure force of the tools when molding the parison into a final shape, such as a finished cover of one family of plastics, causes the heat softened inner layers of the parison to physically engage one another and fuse together. The outer layer or skin of the parison joins with the inner layers at the interface therewith during co-extrusion because of miscibility of the two materials. When the part is being formed in the molding dies, an air passage may be molded into the cover providing ducting for heat and air conditioning. The finished part when removed from the molds can be easily handled because of the structural support of the core while the outer skin provides for the required "soft feel".